Is it possible to slow speeders through an optical illusion? That’s what the Virginia Department of Transportation and its research division, the Virginia Transportation Research Council, hope to learn on a speed-prone section of Lee Chapel Road in Fairfax County.

Similar optical speed bars are being installed on Lee Chapel Road May 3

On Wednesday, May 3, VDOT will install “optical speed bars” -- a series of lines painted at decreasing intervals on the roadway -- that visually give drivers the perception they are moving faster than they intended. The pattern of lines is also meant to get drivers’ attention so they will slow down.

“We chose Lee Chapel Road as a test site because we have a speeding problem on a half-mile segment as well as a higher-than-average crash rate,” said VDOT assistant district traffic engineer Bill Harrell. “We are eager to determine if this potentially low-cost solution can slow down motorists.”

The approximately half-mile section on Lee Chapel Road is located between Route 123 and the Fairfax County Parkway. The roadway immediately north of Route 123 and south of the Fairfax County Parkway has two lanes in each direction with good sight distance. However, the half-mile section between the bridge at South Run and Pond Point Drive is a two-lane stretch that narrows and loses its wide shoulders.

VDOT traffic engineers will evaluate speed data next week and again in three months and will compare that data with the information collected several weeks before the installation of the bars. Magnetic speed detectors are being installed at 10 locations on Lee Chapel Road.

“These optical speed bars will alert motorists to the fact that the road narrows considerably and, we hope, will induce them to slow down so they won’t be driving so fast along this stretch,” said Gene Arnold, senior research scientist at the Virginia Transportation Research Council in Charlottesville. “The main objective is making the road safer for the driver.”

An August 2005 speed study taken just north of the Route 123 intersection showed that 85 percent of northbound motorists drive 15 miles over the 40 mph speed limit and 85 percent of southbound motorists drive about seven miles over the speed limit.

A three-year summary (2002-2004) of crash data between Viewcrest Drive on the south and Pond Point Drive on the north showed an annual crash rate (crashes per 100 million vehicle miles traveled) of 356, 130 and 308, respectively. The average crash rate on secondary roads in Fairfax County is approximately 290 crashes per 100 million vehicle miles traveled.

Senator Jay O’Brien (39th District) and Delegate Dave Albo (42nd District) and Fairfax County Supervisor Elaine McConnell have each expressed support for the pilot project.

The optical speed bars pilot study is a part of a larger project the Virginia Transportation Research Council is conducting for VDOT to determine whether certain safety practices used successfully in other countries will work as well in the United States and Virginia. Total cost of the research project is $100,000 and is expected to be completed in November 2006. VDOT’s cost to install the bars is approximately $2,000.

A British study of optical speed bars found they reduced fatal and serious injury accidents and maintained their effectiveness for four years after the initial data were collected.